Nowadays, renewable energy plays an important role in our daily lives. This Special Issue addresses the current trend in the use of renewable energy in South Korea. The first aspect is a renewable-based power system, where both main and ancillary supplies are sourced from renewable energies; the second aspect is a distribution network for renewable energy; and the last aspect is a nanogrid network technology. Renewable energy requires many innovations over existing power infrastructure and regulation. These articles show the changing trend in various sectors in Korea.